The use of radio frequency (RF) generators and electrodes to be applied to tissue for pain relief or functional modification is well known. For example, the RFG-3B RF lesion generator of Radionics Inc., Burlington, Mass. and its associated electrodes enable electrode placement of the electrode near target tissue and heating of the target tissue by RF power dissipation of the RF signal output in the target tissue. For example, the G4 generator of Cosman Medical, Inc. Burlington, Mass. and its associated electrodes such as the Cosman CSK, and cannula such as the Cosman CC and RFK cannula, enable electrode placement of the electrode near target tissue and heating of the target tissue by RF power dissipation of the RF signal output in the target tissue. Temperature monitoring of the target tissue by a temperature sensor in the electrode can control the process. Heat lessons with target tissue temperatures of 60 to 95 degrees Celsius are common. Tissue dies by heating above about 45 degrees Celsius, so this process produces the RF heat lesion. RF generator output is also applied using a pulsed RF method, whereby RF output is applied to tissue intermittently such that tissue is exposed to high electrical fields and average tissue temperature are lower, for example 42 degrees Celsius or less.
RF generators and electrodes are used to treat pain and other diseases. Examples are the equipment and applications of Cosman Medical, Inc., Burlington, Mass. such as the G4 radiofrequency generator, the CSK electrode, CC cannula, and DGP-PM ground pad. Related information is given in the paper by Cosman E R and Cosman B J, “Methods of Making Nervous System Lesions”, in Wilkins R H, Rengachary S (eds.); Neurosurgery, New York, McGraw Hill, Vol. 3, 2490-2498; and is hereby incorporated by reference in its entirety. Related information is given in the book chapter by Cosman E R Sr and Cosman E R Jr. entitled “Radiofrequency Lesions.”, in Andres M. Lozano, Philip L. Gildenberg, and Ronald R. Tasker, eds., Textbook of Stereotactic and Functional Neurosurgery (2nd Edition), 2009, and is hereby incorporated by reference in its entirety.
The Cosman CC cannula and RFK cannula, manufactured by Cosman Medical, Inc. in Burlington, Mass., include each an insulated cannula having a pointed metal shaft that is insulated except for an uninsulated electrode tip. The cannula has a hub at its proximal end having a luer fitting to accommodate a separate thermocouple (TC) electrode, for example the Cosman CSK electrode, Cosman TCD electrode, and Cosman TCN electrode, that can deliver electrical signal output such as RF voltage or stimulation to the uninsulated electrode tip. The Cosman CSK and TCD electrodes have a shaft that is stainless steel. The Cosman TCN electrode has a shaft that is Nitinol. A disadvantage of this system is that fluid injection into the cannula cannot be achieved when the TC electrode is also in the cannula. Another disadvantage is that the temperature sensor probe and the cannula are separate elements, which increases the complexity of the components needed for the system. Another disadvantage of the Cosman CC and RFK cannula is that its shaft is constructed from stainless steel hypotube. Another disadvantage of the Cosman CC and RFK cannula is its shaft is not flexible enough for epidural placement. Related information is given in Cosman Medical brochure “Four Electrode RF Generator”, brochure number 11682 rev A, copyright 2010, Cosman Medical, Inc., and is hereby incorporated by reference herein it its entirety.
Each injection electrode made by Cosman Medical Inc. (Burlington, Mass.), including the CU electrode, the CR electrode, and the CP electrode models, has a shaft including metal tubing with sharp distal end for insertion into tissue to reach a spinal target. The shafts of the Cosman injection electrodes have lengths 6 cm (2.4 inches), 10 cm (3.9 inches), or 15 cm (5.9 inches). The shaft of a Cosman injection electrode is configured to penetrate the skin surface, muscle, and other tough bodily tissues to enable percutaneous placement of the electrode tip at nerves outside and around the bony spinal column. The shaft of a Cosman injection electrode is insulated except for an exposed conductive tip portion and has an electrical connection to a signal generator for delivery of stimulation or RF signal outputs to the target tissue. Each has a flexible injection tube and a port to allow injection of contrast, anaesthetic, or saline solution fluid to the target tissue. The CU electrode incorporates a temperature sensor positioned within the exposed, conductive tip portion. The CR and CP electrodes do not incorporate a temperature sensor. The CP electrode can be used to effect a stimulation-guided nerve block, whereby an electrical stimulation signal is applied to the CP electrode via its electrical connector, stimulation signals are applied to nerve tissue nearby the conductive tip of the CP electrode, and anesthetic fluid is injected through the CP shaft once desired stimulation response is achieved by positioning of the exposed tip. The CR electrode can be used to effect a stimulation-guided RF therapy without temperature control, whereby an electrical stimulation signal is applied to the CR electrode via its electrical connector, the stimulation signal is applied to nerve tissue nearby the conductive tip of the CR electrode in order to position the exposed tip of the electrode near target nerves, RF generator output is applied to the CR electrode via the same electrical connector, RF output is applied to tissue nearby the exposed tip of the electrode without temperature monitoring. The CR electrode can also be used to effect non-stimulation-guided RF therapy, whereby stimulation guidance is not utilized. The CU electrode can be used to effect a stimulation-guided RF therapy with temperature monitoring and control, whereby an electrical stimulation signal is applied to tissue via the CU electrode to position its exposed tip near target nerves, and RF output is applied to tissue near the exposed tip to effect medical treatment. The CU electrode can also be used to effect non-stimulation-guided RF therapy, whereby stimulation guidance is not utilized. The Cosman injection electrodes are not configured to be positioned by the epidural space. The shafts of the Cosman injection electrodes are not substantially flexible. The lengths of the Cosman injection electrodes' shafts are less than 5.9 inches. The Cosman injection electrodes are not structed using a spring coil. The Cosman injection electrodes are not introduced into the human body via an introducer needle, such as an epidural needle. Related information is given in Cosman Medical brochure “Four Electrode RF Generator”, brochure number 11682 rev A, copyright 2010, Cosman Medical, Inc., and is hereby incorporated by reference herein in its entirety.
In one embodiment, U.S. Pat. No. 7,862,563 by E R Cosman Sr and E R Cosman Jr presents a unitized injection electrode with an electrically-insulated shaft, an exposed metallic tip, a temperature sensor within the exposed metallic tip, cables that connect to the electrode via a single, flexible leader connector that splits into two parts of which the first is terminated by a connector configured to carry high-frequency and stimulation signals and temperature-measurement signals, and the second is terminated by an injection port through which fluid can be injected into the shaft and out the distal end of the electrode. One limitation of this prior art is that it does not show a unitized injection electrode for which the metallic tip and insulated shaft are constructed using a spring coil and a central stiffening wire. One limitation of this prior art is that it does not show the application of a unitized injection electrode in the epidural space.
In the prior art, the Cosman TEW electrode system includes an electrode with a spring-coil tip that has a temperature sensor at its distal closed end. The TEW electrode is introduced into the human body by means of an insulated cannula. The TEW electrode is designed for RF treatment of the trigeminal facial nerve via the foremen ovale of the human skull. The TEW electrode is not electrically insulated. The shaft of the TEW electrode is a metallic tube to the distance end of which is attached a spring coil. The coil tip of the TEW electrode is configured to emerge from the end of the cannula and into the body without diverging substantially from its predetermined curve. The TEW electrode's spring coil is no longer than 0.33 inches. The TEW electrode's spring coil emerges from the distal end of the cannula by no more than 0.33 inches. The TEW electrode is not configured to be threaded through the epidural space. The TEW electrode is not configured to be threaded through 12 inches to 34 inches of the epidural space. The TEW electrode is not long enough to apply RF therapy to multiple spinal nerves via a single skin puncture and the epidural space. The TEW electrode does not have an injection port. The TEW electrode is not configured to allow for outflow of fluids from its spring coil tip. Related information is given in Cosman Medical brochure “Four Electrode RF Generator”, brochure number 11682 rev A, copyright 2010, Cosman Medical Inc., and is thereby incorporated by reference herein in its entirety.
The Cosman Flextrode RF electrode system includes an electrode and an introducer cannula. The flextrode electrode's shaft is approximately 15 cm (5.9 inches) in length and is constructed from a metal tube whose distal end has a spiral cut over the distal 1.25 inches. A temperature sensor is located at the distal, closed end of the shaft. The electrode is induced into the human body via the introducer cannula which has a sharped distal end and whose shaft is electrically insulated. When the electrode is introduced through the cannula, 11 mm of the electrode extends beyond the cannulas distal end into the tissue. The Flextrode electrode is not electrically insulated. RF energy is applied to the tissue by the length of the Flextrode electrode that extends beyond the cannula's distal tip and the uninsulated distal tip of the cannula. The Flextrode is configured to penetrate tissue, such as the fibrous tissue of the intervertebral disc, where it emerges from the distal end of the cannula. The Flextrode's stiffness is configured so that its tip can move through the curved tip of the introducer cannula but remain substantially straight as it penetrates tissue. The Flextrode electrode is not configured for placement in the epidural space. The Flextrode is not configured for injection of fluids into the human body. Related information is given in Cosman Medical brochure “Four Electrode RF Generator”, brochure number 11682 rev A, copyright 2010, Cosman Medical Inc., and is hereby incorporated by reference herein in its entirety.
The Radionics DiscTrode RF electrode system includes an electrode and an introducer cannula. The disctrode electrode's shaft is approximately 9 inches in length and is constructed from a metal tube whose distal end has thin cuts over the distal 2.5 inches. A temperature sensor is located at the distal, closed end of the shaft. The electrode is induced into the human body via the introducer cannula which has a sharped distal end and whose shaft is electrically insulated. When the electrode is introduced through the cannula, 5 cm (2 inches) of the electrode extends beyond the cannula's distal end into the tissue. The disctrode electrode is not electrically insulated. RF energy is applied to the tissue by the length of the disctrode electrode that extends beyond the cannula's distal tip and the uninsulated distal tip of the cannula. The disctrode is configured to penetrate tissue, such as the fibrous tissue of the intervertebral disc, where it emerges from the distal end of the cannula. The disctrode's stillness is configured so that its tip can move through the curved tip of the introducer cannula but remain substantially straight as it penetrates tissue. The disctrode electrode is not configured for placement in the epidural space. The disctrode is not configured for injection of fluids into the human body. Related information is given in an article by P M Finch entitled “The Use of Radiofrequency Heat Lesions in the Treatment of Lumbar Discogenic Pain”, Pain Practice, Volume 2, Number 3, 2002, pages 235-240, which is here incorporated by reference herein in its entirety.
The Oratec Spinecath system includes a catheter and an introducer cannula. The catheter's shaft consists of a resistive coil that is entirely covered by electrical insulation. RF energy applied to the coil heats the internal resistive coil and tissue is heated by thermal conduction. RF energy is not applied to the tissue. A temperature sensor is located in the spinecath catheter. The electrode is induced into the human body via the introducer cannula which has a sharped distal end. The spinecath emerges from the distal end of the cannula by approximately 5 cm (2 inches). The spinecath catheter is not configured for placement in the epidural space. The spinecath is not configured for injection of fluids into the human body. Related information is given in an article by PM Finch entitled “The Use of Radiofrequency Heat Lesions in the Treatment of Lumbar Discogenic Pain”, Pain Practice, Volume 2, Number 3, 2002, pages 235-240, which is here incorporated by reference herein in its entirety.
The use of catheters in the epidural space to treat pain is well known. A flexible catheter is introduced into the epidural space through an epidural needle inserted percutaneously through the sacral hiatus, through an intervertebral foramina, or through vertebral interspaces. An injection adaptor, such as a tuohy-borst adaptor, can be attached to the proximal end of the catheter to provide for the injection of fluids into the proximal end of the catheter that outflow into patient anatomy through the distal end of the catheter. Techniques such as lysis of adhesions, chemical neurolysis of nerve roots, and other medial methods are well known. Examples of epidural catheters include the Tun-L-XL catheter manufactured by EpiMed International, Farmers Branch, Tex. The Tun-L-XL catheter comprises a stainless steel spring coil whose distal end is welded into a ball, and which is covered by a plastic tube over its entire length except for the distal end. The coil wire is closely coiled except for a region of the exposed, distal coil where the cool loops are loosely wound to provide for preferential outflow of injected fluids. The coil can have a metal safety strap welded at the proximal and distal end of the coil. A stylet comprising a metal wire and a plastic hub attached to the proximal end of the wire, is inserted into the proximal end of the catheter to stiffen it. The stylet is removed, an injection adaptor is attached to the proximal end of the catheter, and fluids can be injected. Nerve stimulation signals can be delivered through the exposed metallic tip of the catheter by connecting the proximal end of the stylet to the output of a nerve stimulator, perhaps by means of an alligator clip, while the stylet is positioned inside the catheter. Related information is in “Epidural Lysis of Adhesions and Percutaneous Neuroplasty” by Gabor B. Racz, Miles R. Day, James E. Heavner, Jeffrey P. Smith, Jared Scott, Carl E. Noe, Laslo Nagy and Hana Ilner (2012), in the book “Pain Management—Current Issues and Opinions”, Dr. Gabor Racz (Ed.), ISBN: 978-953-307-813-7, InTech, and is hereby incorporated by reference in its entirety. One disadvantage of the prior art in epidural catheters is that an electrode with a temperature monitoring is not used as a stylet. One disadvantage of the prior art in epidural catheters is that the stylet does not have an integrated connection cable to an electrical generator. One limitation of the prior art in epidural catheters is that electrical stimulation cannot be applied at the same time that fluid is injected through the catheter. One limitation of the prior an in epidural catheters is that prior catheters do not provided for temperature-controlled RF lesioning. One limitation of the prior art in epidural catheters is prior catheter systems have multiple pieces. One limitation of the prior art in epidural catheters is prior catheter systems are not a unitized injection electrode.
U.S. Pat. No. 6,246,912 by M E Sluijter, W J Rittman, and E R Cosman presents in FIG. 9 a catheter electrode with one or more electrical contacts, where the catheter electrode is placed in the epidural space and applies high frequency signals via its electrical contacts. The electrical contact are tubular rings bonded to the substrate catheter and connected to wires internal to the catheter. The catheter may have reinforced metal spirals in its construction. The catheter electrode does not provide for the injection of fluids. The catheter electrode does not apply high frequency signals to the tissue by the same spring coil that is part of its shaft construction.
U.S. Pat. No. 8,075,556 by A Betts presents a specific construction of a device configured for placement in the spinal canal and delivery of RF energy. Betts describes a catheter delivery device to transmit radiofrequency energy to a spinal canal, comprising: a needle having an open proximal end and an open distal end, and a lumen that extends from the open proximal end to the open distal end; a catheter having a blunt, metallic tip on a distal end of the catheter that transmits a radio frequency energy to the treatment site, wherein the catheter is telescopically disposed within the needle lumen to allow the tip to be maneuverably positioned within the spinal canal; a catheter hub coupled to a proximal end of the catheter a metallic wire element telescopically disposed within a lumen of the catheter; and an adapter hub coupled to a proximal end of the wire element, wherein the adapter hub is cooperatively engageable to the catheter hub to form a single shaft, wherein a proximal end of the adapter hub is configured couple to a radio frequency generating device, and wherein the adapter hub and the catheter hub are sized and dimensioned relative to one another such that engagement of the adapter hub to the catheter hub allows a distal end of the wire element to touch a seating surface of the tip such that the wire element delivers a radio frequency energy from the radio frequency generating device to the tip. A disadvantage of the prior art in Betts is that the catheter has an adaptor hub. A disadvantage of the system described in Betts is that a standard epidural catheter is not used. A disadvantage of the system described in Betts is that construction of the catheter using a metal coil is not described. A disadvantage of the system described in Betts is that a safety strap within the catheter shaft is not described; a disadvantage of the absence of a metallic safety strip is that the impedance of the catheter shaft can distort and/or diminish electrical signals conducted along the shaft. A disadvantage of the system described in Betts is that RF is not delivered without seating of the RF wire in the inner surface of the distal end of the catheter. A disadvantage of the system described in Betts is that the system does not provide temperature monitoring. A disadvantage of the system described in Betts is that the system does not provide for temperature-monitored RF therapy delivered through the catheter. A disadvantage of the system described in Betts is that the RF wire does include a temperature sensor. A disadvantage of the system described in Betts is that it not a unitized injection electrode. A disadvantage of the system described in Betts is that the RF wire is separate from the catheter. A disadvantage of the system described in Betts is that injection through the catheter cannot be effected while the RF wire is in place within the catheter. A disadvantage of the system described in Betts is that it does not provide for simultaneous injection of fluids and delivery of electrical signals.
U.S. patent application 2004/0210290 by Omar-Pasha describes a catheter electrode for pulsed RF treatment of nerves in the epidural space. One limitation of this prior art is that does not describe the use of a coil to construct the catheter electrode. Another limitation of this prior art is it does not describe an RF electrode system in which an RF electrode stylet is inserted into a standard epidural catheter.
The pulsetrode electrode manufactured by BioAmpere Research SRL, Verona, Italy is a flexible electrode comprising a plastic shaft, three ring electrodes near its distal end, a hub, an injection port connected to a tube that is connected directly to the hub, a generator wire that connects directly to the hub, a moveable stylet is inserted into the injection port and travels along the shaft of the electrode. The pulsetrode is configured for placement in the epidural space and delivery of radiofrequency fields to anatomy. Related information given in Bioampere Research brochure “Pulserode” and is hereby incorporated by reference herein in its entirety. One limitation of this prior art is that does not describe the use of a coil to construct the catheter electrode. Another limitation of this prior art is it does not describe an RF electrode system in which an RF electrode stylet is inserted into a standard epidural catheter. Another limitation of this prior art is that the distal end of the electrode is electrically insulated. Another limitation of the this prior art is that the active tip is not the sole active tip.